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Austropyrgus nitidus (Johnston, 1879)

Diagnostic features

This species belongs to the Austropyrgus sparsus group, whose members are characterised by the following shell features: small to medium sized shells, conical, with convex to slightly convex whorls. Furthermore, in females, the coiled oviduct is of an inverted U-shape or with two or more bends, loops or twists.

Austropyrgus nitidus differs from the other species of this group in the following combination of characters: shell small to medium in size, with straight spire outline and convex whorls; seminal vesicle tightly coiled over stomach; pallial vas deferens straight at prostate gland; coiled oviduct and bursal duct join well behind posterior pallial wall.

Classification

Austropyrgus nitidus (Johnston, 1879)

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Austropyrgus Cotton, 1942

Original nameBithynella nitida Johnston, 1879. Johnston, R. M. (1879). Further notes on the fresh-water shells of Tasmania (with a description of new species). Papers and Proceedings of the Royal Society of Tasmania 1877: 19–29.

Type locality: Thunder and Lightning Bay, Cape Barren Island, Bass Strait, Tasmania (Quaternary fossil deposits).

Biology and ecology

On water weeds, hard substrate (rocks etc.) and crawling on sediment. Can be locally abundant. Assumed to feed by scraping bacteria and microalgae. Presumed solitary capsules with single egg. Direct development.

Additional information on the biology and ecology of members of this family can be found in Fauna of Australia, vol. 5B, p. 752-755.

Distribution

This species is found in the small streams and rivers of Flinders and King Islands and some of the other smaller islands of Bass Strait.

Notes

Although most species of Austropyrgus are geographically isolated and have restricted ranges, a few - such as A. nitidus - have wider ranges. This is the only species of Austropyrgus living on the Bass Strait islands.

This species was named from Quaternary deposits but the living material from the same area is very similar and treated as the same species by Clark et al. (2003).

Further reading

Clark, S. A., Miller, A. C. & Ponder, W. F. (2003). Revision of the snail genus Austropyrgus (Gastropoda: Hydrobiidae): a morphostatic radiation of freshwater gastropods in southeastern Australia. Records of the Australian Museum 28: 1–109.